For filling:
Peel an onion (one large or two medium-sized ones) and cut into half rings, bacon into strips, and wash the mushrooms and cut into small slices.
First fry the onion, add just a pinch or two of sugar – for caramelization. Then add the bacon so it’s just fried, and the mushrooms! Leave to fry for 5-7 minutes. At the end, add the cream, mix well, season with salt and pepper and remove from the stove. Let the filling cool down a little.